1. Field of the Invention
The present invention relates to a Stirling engine, and more particularly to the heater of the Stirling engine suitable for air-conditioning, heating and generation of electric power.
2. Description of the Related Art
A conventional Stirling engine has a reversible cycle which comprises two isothermal changes and two equivalent changes. Namely, the Stirling engine has a cycle in which cold (isothermal) compresses the operational gas such as helium enclosed therein with the external cooling (generally, the operational gas is water cooled by a cooler) and in which heat (isothermal) expands operational gas with the external heating (generally, the operational gas is heated by the combustion heat supplied to a heater). In the Stirling engine having a cycle of this sort, the waste heat left to the cooling water of the cooler is larger than 50% of the input heat supplied to the heater. By the use of the Stirling engine, it is possible to improve the efficiency of the use of the energy due to using the waste heat for heating and suctioning of hot water. Further, the heat efficiency is high, hazards to the public minimal and it is able to use a variety of fuels. As a result, the Stirling engine is suitable as the power source of the compressor for a air-conditioning and heating device.
In the Stirling engine, the efficiency of the heat transfer between the heat and the combustion gas largely influences the efficiency of the Stirling engine.
In the conventional Stirling engine, the heat-exchanger of the multi-pipe type or the bayonet type, for example, is shown by U.S. Pat. Nos. 4,069,670 and 4,7I9,755, respectively. In these heaters, however, since there are many parts which constitute the heater and there are many brazing points and welding points. Therefore, the number of manufacturing steps increase and the manufacturing costs increase. Further, in these heaters, scaling of the heater causes an increasing heat transfer area of the heater.